Hardness measuring machines can be classified in various ways. According to one of these there are locally installed and mobile hardness testers. The colleagues of MultiLab Kft. can calibrate these instruments and devices on-site or in the laboratory of the company, depending on which category they belong to.
According to the standard pertaining the inspection of installed harness measuring devices, the calibration shall include the following verifications:
Full name of relevant inspection standard:
MSZ EN ISO 6506-2
Brinell hardness test
Part 2: Verification and calibration of hardness testing machines
Direct verification
Indirect verification (function test)
Full name of relevant inspection standard:
MSZ EN ISO 6507-2
Vickers hardness test
Part 2: Verification and calibration of hardness testing machines
Direct verification
Indirect verification (function test)
Full name of relevant inspection standard:
MSZ EN ISO 6508-2
Rockwell hardness test
Part 2: Verification and calibration of hardness testing machines
Direct verification
Indirect verification (function test)
It is worth mentioning the points regarding the frequency of calibration in the standards for hardness measuring instruments, according to which:
Quote from the MSZ EN ISO 6506-2, MSZ EN ISO 6507-2 and MSZ EN ISO 6508-2 standards:
„6. Interval between verifications
6.1. Direct verification
Direct verification shall be done:
Each direct verification shall be followed by an indirect verification.
6.2. Indirect verification
The time interval between two indirect verifications depends on the maintenance instruction of the machine and on the frequency of use. This interval shall under no circumstances be longer than 12 months.”
The essence of the Brinell method is that a steel ball measuring body is pressed into the surface to be measured and the hardness is defined as the quotient of the loading force and the spherical cap indentation. Since the force and the surface of the indentation are not proportional, both the indenting tool and the loading force had to be standardized.
The size of the ball shall be selected according to the object to be measured. Thus the size of the ball can be: 2.5 mm; 5 mm and 10 mm
The loading force needs to be adjusted to the anticipated hardness of the object to be measured. Thus the loading force can be: 5D2; 10D2; 20D2 és 30D2
E.g.: In case of steel it is 30D2, which equals to a 10 mm ball / 3000 kp, that is 3000x9,81 N loading force.
The sign of the Brinell hardness test is: HB (which stands for Hardness Brinell)
For example: HB 10/3000/30 which indicates the size of the ball in millimetres, the loading force in kp and the time of the load in seconds.
The method is used for the testing of materials with a hardness below HB 400. At higher hardness the steel ball is deformed, thus in such a special case the ball to be used shall be made of wolfram carbide. The sign in that case is: HBW, in order to refer to the wolfram carbide ball
The ball indent is either read from the measured object or from a projection with a precision of 0.01 mm.
Some typical parameters concerning the Brinnell test
Tool: hardened steel ball
| D diameter of the ball /mm/ | Thickness of test piece |
| 10 | above 6 mm |
| 5 | between 3-6 mm |
| 2,5 or 1,25 | below 3 mm |
| Loading force = F1 x 9,81 ( N) | Loading time t (s) | ||
| Material | F1 | Material | Time |
| Steel, cast iron | 30 x D2 | Hard (steel, alloy) | 15 |
| Al, copper, bronze | 10 x D2 | Medium (Cu, Al) | 30 |
| Al-Zn alloys | 5 x D2 | Soft ( Pb) | 180 |
| Lead, tin bearing alloy | 2,5 x D2 | ||
The essence of the hardness measurement is that the indenting tool is a diamond pyramid. Hardness is interpreted as the quotient of the loading force and the surface of the indentation. Since these are proportional to each other with a good approximation, in case of the Vickers hardness test the loading force is freely selectable.
The indication of hardness is HV 10/30, which refers to the loading force and the time of loading.
Under a microscope, gram loads can be used to measure the microhardness of the individual phases. For local measurements of fine tools and parts, measurements are usually performed with a loading force of 0.5-1 x 9.81 N, and usually 10 kp / 10 x 9.81 and 30 kp / 30 x 9.81 N. An obstacle to further increasing the loading force, especially in case of soft materials, is the size of the diamond.
The imprint is either read from the measured object or from a projection with a precision of 0.001 mm.
Tool: Diamond pyramid with a planar angle of 136 degrees.
Loading force: freely selectable, mainly depending on the thickness and hardness of the object to be measured.
The most universal hardness testing method, applicable both to soft and hard materials.
The Rockwell method derives the hardness from the depth of the indentation caused by different penetrating bodies and different loads. This has both advantages and disadvantages. Its advantage is that the hardness can be automatically and simply derived from the sign of the displacement. Its disadvantage is the lower accuracy as compared to the Vickers test. The sign of the Rockwell hardness test is: HR (from the English term Hardness Rockwell) Depending on the type of the penetrating body and the load applied to the indentation, there are different Rockwell “scales”. The three most common are:
The three above Rockwell methods are the most common, but there are also other Rockwell testing methods.